The need for a standardized protocol for communication with media devices has been addressed with the development of the Media Transfer Protocol (MTP), an advanced, publicly defined protocol which may be used to link to MP3 players, video playback and other media devices to personal computers or other clients. As with other protocols designed for other purposes, the Media Transfer Protocol defines a set of commands, data structures and other standardized schema which permit devices to talk to each other compatibly and reliably, even if the devices are made by different manufacturers or have never communicated before. In the case of MTP, the native commands and data structures of that protocol may facilitate, for example, the object-oriented retrieval and management of media files, such as MP3 or other audio files, Windows™ Media video files, or other files or formats. Device manufacturers, software developers and others may incorporate such transport or other protocols to leverage advantages of lower cost and greater compatibility in their products. However, establishing a precisely defined standard can also entail certain disadvantages as well.
Among those disadvantages is the lack of a ready way to enable vendor-specific extensions to the protocol. Protocol extensibility has been implemented in a fashion in the past, for instance to permit vendors to specify vendor-specific fields or modes appended to the normal data structures of the protocol. However, even when those limited protocol extensions have been possible, they have in general been generated by way of a standards body distributing approval for those extensions and defining them for members upon request. For instance, extensions to the Picture Transfer Protocol (PTP) used in digital cameras and other products have been possible only through human-reviewed designation by the Photographic and Imaging Manufacturers Association (PIMA), now inactive. Delegating the task of assigning extensions to a third party body has the advantage that definitions may be defined in a mutually exclusive way, so that the commands or other extensions of one manufacturer may be ensured to not interfere with that of another manufacturer. For example, address spaces or command definitions may be divided so that operations do not conflict. However, the mechanism of human-reviewed standards approval may often be a cumbersome process, so that individual vendors may not be able to quickly implement or reliably verify protocol extensions for their hardware, software or other purposes. Other problems in the technology and process of protocol design exist.